A) Field of the Invention
The present invention relates to a micromanipulator system equipped with a microscope, and more particularly to a micromanipulator system configured to three-dimensionally manipulate a fine tool wherein a multi-direction control joystick coupled to a plurality of stepper motors moves the tool within the field of view of a microscope, the stepper motor having a stepper angle that is subdivided into preselected reference subdividing units.
B) Description of Related Art
In current biological research, for instance where a DNA solution is injected into a cell, fine and delicate manipulation of precise tools is necessary. Micromanipulator systems have been developed which include a fine needle mounted on a micromanipulator. Such work is usually associated with a microscope for observing the cell and the injecting process. In the micromanipulator system of this type, a joy stick for X- and Y-axes which is tiltable forward and backward and rightward and leftward.
There are many case where the fine instrument such as the fine needle which is held to a tip of the micromanipulator is usually arranged with an inclined angle with respect to a horizontal plane (X-Y plane). Accordingly, for the purpose of moving the fine instrument in a longitudinal direction thereof, it is necessary to drive the fine instrument in a synthetic direction which synthesizes a horizontal direction (X-axial direction, Y-axial direction or its synthetic direction) and a vertical direction (Z-axial direction). In the above-mentioned joy stick, it is difficult to manipulate the fine instrument simultaneously in a plurality of directions in accordance with the longitudinal direction of the fine instrument. In particular, it is difficult to perform the movement control of the fine instrument with accuracy.
To drive the micromanipulator along the three axis directions (X-axis, Y-axis, Z-axis directions), stepper motors are independently employed along the respective axial directions. A stepper motor can achieve highly precise positioning in response to the number of input pulse.
Problem to be Solved
Further, as mentioned above, the fine instrument is arranged with an inclined angle with respect to the horizontal plane (X-Y plane), and to perform the fine vibrations by use of the usual micromanipulator, it is necessary to drive the fine instrument in the synthetic directions more than two axes. In the conventional micromanipulator, because no structure in which the fine instrument is moved at an arbitrary angle, it is difficult to perform such fine vibrations along the longitudinal direction of the fine instrument.
Moreover, in the case where the tip position of the fine needle is moved by use of the joy stick while being recognized with eyes through a microscope or the like, it is difficult to move it to a target position with accuracy. Even in this case, the fine needle is required to move along the longitudinal direction, and the conventional micromanipulator cannot make the fine needle move at an arbitrary angle for an arbitrarily set distance with accuracy.
In the case of providing the manipulator for moving the fine instrument along the longitudinal direction, the number of parts is increased, the device is large-sized and it is difficult to reduce the costs. Also, it is necessary to additionally provide a manipulating section for manipulating that manipulator, resulting in troublesome in manipulation.
It is considered that a micromanipulator of the friction type is used which is general in the field of the micromanipulator, and as movement modes of the micromanipulator, there are provided a speed control mode in which an actuator is driven at a speed corresponding to the inclined amount of the manipulating lever for the joy stick and a position control mode in which the actuator is driven by a distance corresponding to the inclined amount of the manipulating lever, and switching between both the control modes are performed by a change-over switch provided on the manipulating panel.
However, in that construction, when the mode is switched from the position control mode to the speed control mode under the state where the joy stick is inclined, an arm portion of the micromanipulators automatically starts to be moved regardless of the intention of the operator (comes to a runaway state).
With the above-described conventional arrangement, the positional relationship within the horizontal axis may be judged with respect to the positional relationship between the fine sample and the fine instrument, while observing the display screen. However, the positional relationship with respect to the Z-axis direction (i.e., height direction) should be judged based on only the focal shift. For instant, the positional relationship along the height direction is judged by focalizing the fine sample and subsequently focalizing the fine instrument. As a result, only a highly experienced operator can judge this positional relationship along the height direction, and therefore most of the operators meet difficulties to judge such a height positional relationship and to manipulate the fine instrument. This would impede an improvement in operabilities of the micromanipulator.
In the above-mentioned micromanipulator system, when the pulse generator by the calculation means is employed, it is practically difficult to produce the pulses at the high frequencies. Thus, it is technically is difficult to increase and/or continuously vary the moving speed of the micromanipulator.
Furthermore, in the micromanipulator system, there are many possibilities that the fine instrument held at the tip portion is arranged in such a manner that it is inclined with respect to the horizontal plane (X-Y plane) at a certain angle. In order that such a fine instrument is moved along a longitudinal direction thereof, the micromanipulator must be driven along such a direction defined by synthesizing a plurality of axial directions. The moving amounts of the micromanipulator along the respective axial directions may be determined by a ratio of manipulation amounts based on the moving angle. However, when the stepper motors along the respective axial directions are driven in accordance with the above-described manner, since the moving speeds are discontinued, it is difficult to smoothly move the manipulator along the longitudinal direction of the fine instrument. Accordingly, there is a risk that the movement of the micromanipulator represents a coasting. To prevent such a coasting, the control period as well as the maximum speed may be improved. However, under such an improvement, high cost components are necessarily required, which may impede cost down solutions.